Integrated safety disconnects for power systems

ABSTRACT

Various embodiments provide safety disconnect systems for a power system. In one aspect, a safety disconnect system includes an enclosure operative to receive a plurality of input power lines into the enclosure and provide a plurality of output power lines out of the enclosure. Each input power line is coupled to and paired with a corresponding one of the output power lines, where each input power line and output power line is operative to provide power from a power source. A plurality of switches are provided in the enclosure, each of these switches coupled between an associated one of the pairs of input power line and output power line, and each switch operative to disconnect the associated input power line from the corresponding output power line.

FIELD OF THE INVENTION

The present invention relates to power distribution systems, and moreparticularly to safety disconnects for power systems.

BACKGROUND OF THE INVENTION

In the field of power distribution, power feeds from several powersources may be used to provide power to a power distribution unit. Forexample, in solar power systems, power inputs from several solar panelscan combined using combiners and/or recombiners having one or moreoutputs provided to an inverter or other component of the power system.

Operators of the power system may have a need to disconnect one or moreof the power inputs from power sources. For example, if one of the powersources fails, or a connection in the system fails, then the powerinputs need to be disconnected from the load so that the faultycomponents can be repaired or replaced without exposing the workers tohigh voltage or current. In typical power systems, a safety switch canbe connected between a power source and other component using the power.For example, a safety switch can be connected between a combiner and aninverter in a solar power system, or between a combiner and arecombiner.

A problem with existing safety switches is that they are expensive andlabor-intensive to install and maintain. Typically one safety switch isprovided in each enclosure, such as a metal cabinet, and severalenclosures must be provided to allow safety disconnects for severalpower lines. A conduit with heavy protective cladding must be routedfrom a power connection to each safety switch enclosure. If multiplepower lines are used, such as in solar power systems, a safety enclosureon each power line becomes burdensome and expensive to install andcumbersome to operate and maintain.

SUMMARY OF THE INVENTION

A system and method for providing integrated safety disconnects forpower systems is disclosed. In one aspect, a safety disconnect systemfor a power system includes an enclosure operative to receive inputpower lines into the enclosure and provide output power lines out of theenclosure, each input power line coupled to and paired with acorresponding one of the output power lines. Each input power line andoutput power line is operative to provide power from a power source. Aplurality of switches are provided in the enclosure, each of theseswitches coupled between an associated one of the pairs of input powerline and output power line. Each switch is operative to disconnect theassociated input power line from the corresponding output power line. Inanother aspect, a method for providing a safety disconnect systemprovides similar features.

Some embodiments can include additional features. Each switch can beoperative to disconnect the associated input power line from itscorresponding output power line independently of the connections of theother input power lines and output power lines. The enclosure can belocated on a ground surface, and can include a bottom panel operative toallow the input power lines and the output power lines to be routed intothe enclosure from the ground surface through the bottom panel. Theswitches can each include a rotatable handle, and/or can be included ina circuit breaker. The switches can be accessible behind an opening doorof the enclosure, and a safety panel behind the door can be openable byan operator only in response to opening all of the switches such thatall of the input power lines and output power lines are disconnected.

A current sensing system can be included in the safety disconnectsystem, operative to sense a current flowing through each pair of inputpower line and output power line. At least one of the input power linesand output power lines can include an adaptor coupled between this powerline and the associated switch, the adaptor including a bend to allowconnection between an end of the at least one power line and an inputterminal having lengthwise axes at different angles. The input powerlines can receive power from at least one solar panel, e.g., connectedto at least one string combiner that receives power from at least onesolar panel. The output power lines can be connected to at least onerecombiner that combines the output power lines into a lesser number ofpower lines.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of one example of a power supply systemsuitable for use with one or more embodiments described herein;

FIG. 2 is a front view of a first example of a safety disconnect systemincluding features described herein and using rotatable switch handles;

FIG. 3 is a front view of a dead front of the enclosure of the system ofFIGS. 2-3;

FIGS. 4A-4B are side and front views, respectively, of one example ofthe interior of the enclosure of a safety disconnect system of FIG. 2;

FIGS. 5 and 6 are front views of a second example of a safety disconnectsystem including features described herein;

FIGS. 7A-7B are side and front views, respectively, of one example ofthe interior of the enclosure of a safety disconnect system of FIGS.5-6; and

FIG. 8 is a detail view of an alternate embodiment of a connectionadaptor which can be used with some embodiments of a safety disconnectsystem.

DETAILED DESCRIPTION

The present invention relates to power systems and more particularly tointegrated safety disconnects for power systems. Various modificationsto the preferred embodiments and the generic principles and featuresdescribed herein will be readily apparent to those skilled in the art.Thus, the present embodiments are not intended to be limited to theexamples shown but are to be accorded the widest scope consistent withthe principles and features described herein.

Embodiments described herein provide a compact and inexpensive safetydisconnect enclosure for power systems, in which multiple power linescan be disconnected from the system. The multiple power lines can berouted to a single enclosure that integrates multiple safetydisconnects. This allows greater flexibility in disconnecting particularlines, troubleshooting supply problems, and positioning the disconnectswithout requiring multiple disconnect boxes as in previousimplementations.

As used herein, the terms “include,” “including,” “for example,” “e.g.,”and variations thereof, are not intended to be terms of limitation, butrather are intended to be followed by the words “without limitation.”

FIG. 1 is a block diagram of one example of a power supply system 10suitable for use with one or more embodiments described herein. System10 can include a number of sources 12 which provide electrical currenton output wires 14. The sources 12 can be, for example, solar panelsand/or photovoltaic cells in a photovoltaic system or other system whicheach generate current based on exposure to light, such as sunlight. Eachoutput wire 14 from a power source 12 is connected to a string combiner16, which combines the different currents on wires 14 into a singleoutput 18.

The string combiner output 18 can be connected as an input power line toa safety disconnect system 20, which receives an input power line fromeach of multiple string combiners. For example, a second set of powersources 22 can output current on associated wires 24 that are connectedto a string combiner 26, and the string combiner 26 combines thesecurrents into an output 28 connected to the safety disconnect system 20as an input power line. Additional string combiner outputs can also beconnected to safety disconnect system 20. The power lines 18 and 28 areincluded in the input power lines 22 which are input to the safetydisconnect system 20. The disconnect system 20 provides outputs asoutput power lines 30, where each output power line corresponds to andis paired with one of the input power lines. For example, output powerline 32 can correspond to input power line 18, and output power line 33can correspond to input power line 28. The output power lines 30 can beconnected to a recombiner 34, which combines the currents from themultiple lines 30 into a single output 35 which can be provided to otherpower components, such as an inverter 36 that converts the DC currentfrom the recombiner into AC current for typical home or business use.

In the described example, the disconnect system is placed closer to thepower source than the recombiner, allowing more protection to the usersince there is less current on each power line at such stages. In otherembodiments, the safety disconnect system 20 can be connected the outputof one or more recombiners 34. Alternatively, power sources 12 and 22can be directly connected to the safety disconnect system 20. Thedisconnect system 20 provides switches to allow disconnecting any or allof the power lines from any downstream components or loads of the powersystem.

Other systems suitable for use with the features described herein canalso or alternatively include other or different types of power sourcesthan solar panels 12 and 22. For example, other power systems providingDC current may be similar to solar power systems and can take advantageof one or more of the features described herein, as well as other typesof power systems.

FIGS. 2 and 3 illustrate a first example safety disconnect system 100including features described herein and using rotatable switch handles.For example, system 100 can be an example of a safety disconnect system20 used in a system as shown in FIG. 1, or used in other power systems.

FIG. 2 is a front view of a system 100. System 100 includes an enclosureor housing 101 that holds the components of the system. The enclosure101 is shown in FIG. 1 as an upright cabinet, typically made of asuitable protective and/or weatherproof material such as a metal (steel,stainless steel, etc.), fiberglass, or plastic. The enclosure 101 can bea free-standing cabinet situated on a ground surface such as a floorthat requires a simple, less costly installation than typical mountedsafety disconnect boxes that are connected to wall surfaces above aground surface. In some embodiments, the enclosure 101 has a smallfootprint, e.g. is narrow in length and width, allowing it to be placedin a large variety of locations. A small height also contributes to thecompactness of the enclosure, allow flexibility in its placement. Otherenclosure configurations and shapes can be used in other embodiments. Alockable door 102 can be openable by a handle 103 and protects the innercomponents and prevents easy access to the power components for safetyreasons.

FIG. 3 is a front view illustrating a dead front 104 of the enclosurewhich is located behind the door 102 and exposed when the door isopened, and is a second safety feature to protect operators from thecurrent and voltage of the system 100. A number of rotatable switchhandles 106 are accessible in this example, where each switch handle 106is connected to a switch corresponding to one of the input power linesand one of the corresponding output lines of the system 100.

Each switch handle 106 can be rotated by an operator, e.g. by 90 degreesor other amount in other embodiments, to open the associated switchconnected between associated input and output power lines, therebydisconnecting the portion of the power system that is downstream of thesafety disconnect system 100 (connected to the output power lines) fromthe power provided on the input power lines. This allows an operator toconveniently disconnect power on individual lines which need servicingor for test purposes.

In some embodiments having a dead front 104, a safety feature can beincluded that requires that all the switch handles 106 be rotated to anopen (disconnecting) position to disconnect the power on all lines,which allows the dead front panel to be opened by an operator to exposethe components located behind the dead front 104.

In a solar power system, for example, the multiple power lines connectedto the disconnect system each may carry a DC voltage. To isolate anycomponent of the system, all the power lines must be disconnected. Ifonly one or less than all lines are disconnected, then the connectedsources can backfeed to the disconnected line(s) through the load,creating a live line where a disconnected line is desired.

FIGS. 4A and 4B are side and front views, respectively, of one exampleof the interior of the enclosure of the safety disconnect system 100 ofFIG. 2. The front view of system 100 shown in FIG. 4B has the dead front104 removed. System 100 includes multiple switches 120 which, in thepresent example, are arranged in approximately linear vertical columnlayout with respect to the side view of FIG. 4A. The switches are alsoarranged in this example such that they are positioned in an approximatevertical column with respect to the front view of FIG. 4B. Each switch120 is connected to a switch handle 106 by a shaft 122, such thatrotating the handle 106 by an operator (e.g. as shown by arrow 108)rotates the central member of the corresponding switch to close or openthe switch depending on the direction of rotation.

A staggered vertical orientation of the disconnect switches 120 as shownin FIG. 4A, in which some of the switches 120 are offset on a differentvertical axis to allow some overlap of switches in the verticaldimension. This arrangement can be used in some embodiments to allow agreater number switches to be placed in a particular vertical dimension,thus allowing the enclosure 101 to have a smaller overall verticaldimension. This can be useful, for example, for larger switches 120 thatcan handle greater magnitudes of currents. In other embodiments, smallerswitches 120 designed for smaller currents can be used, which are smallenough to be stacked in an approximate vertical column without suchstaggering (similar to the circuit breakers of FIGS. 7A-7B, below). Theapproximate vertical column of switches 120 also allows the enclosure101 to have smaller width and length dimensions and have a smallfootprint, increasing the ease and flexibility of installation. In someembodiments, all the disconnect switches needed by the power system canbe included in the single enclosure 101. Some embodiments can providesome or all of the switches 120 to be connected in series.

Multiple input lines 126 are routed into the enclosure on one side ofthe switches 120, and corresponding multiple output power lines 130 arerouted out of the enclosure on the other side of the switches 120. Inthe example of FIGS. 4A and 4B, each switch 120 has a terminal 124connected to an associated input power line 126 on one side of theswitches, and has a terminal 128 on the other side of the switchconnected to an associated output power line 130. Some embodiments can,as shown, route the input power lines 126 and output power lines 128through one or more openings in a bottom panel 132 of the enclosure 101.

Each switch 120 thus operates to connect or disconnect the associatedpair of input power line 126 and output power line 128 connected to thatswitch 120, based on the position of the handle 106 connected to theswitch. The single enclosure 101 houses multiple disconnect switches forthe multiple power wires, allowing selective disconnect ability for eachindividual power line, and allowing all the power lines to be routed toa single enclosure. This configuration reduces expense compared toproviding a separate enclosure for each disconnect option on each powerline. Furthermore, in some embodiments, the power lines 126 and 130 canbe routed into the enclosure 101 via an opening in a bottom panel of theenclosure as shown in FIG. 4B, such that these power lines are notexposed and do not need to be enclosed in a protective cladding or otherprotection or safety barrier, thereby decreasing the cost as compared toprevious disconnect systems.

In some alternate embodiments, multiple switches can be combined and beassociated with a single handle 106. For example, two switches 120 canbe positioned along the same horizontal axis of a single shaft 122 suchthat the single shaft 122 is connected to both switches. In the exampleof FIG. 4A, an example of a second switch is indicated by dashed lines121. In response to the associated handle 106 being rotated, both ofthese switches 120 and 121 are opened or closed simultaneously. Thisarrangement allows fewer handles 106 to be used for a larger number ofswitches 120 and power line pairs, which may be required if there is alimit to the number of handles allowed on the enclosure 101.

In some embodiments, fuses can be provided connected to the switches120. For example, a fuse can be connected between each input power line126 and the associated switch 120. Such fuses can provide automaticovercurrent protection.

The disconnect system 100 (or other system embodiments described herein)can in some embodiments include electronic current monitoring. Forexample, a monitoring sensor 140 can be included in or connected to eachswitch 140 or each input or output power line for monitoring currentpassing through that switch 120 or through the associated power line. Inthe described embodiment, a monitoring sensor 140 is shown connected ona jumper connected between two of the poles of each multi-pole switch120 to monitor the current going through or into the switch. Forexample, sensor 140 can be a Hall Effect sensor in the approximate shapeof a ring that is placed around the jumper contact, wire, or power lineconducting the current that is measured. Other types of sensors canalternately be used. Each sensor 140 can be in communication via wiredor wireless connection with one or more controllers or devices (notshown) that can receive signals from the sensors 140 and provide anoutput indicating the magnitude of current sensed by each sensor 140,and this output can be provided to an operator using a display screen orother connected output device. In other embodiments, the sensor 140 canbe placed around input or output terminals to the switches 120, aroundthe input wire 126 to each switch 120, or around the output wire 130from each switch.

FIGS. 5 and 6 illustrate a second example of a safety disconnect system200 implementing aspects of the features described herein and suitablefor use, for example, in a system such as shown in FIG. 1. System 200includes an enclosure or housing 201 that holds the components of thesystem, which in this example is shown as an upright cabinet similar toFIG. 2. Other enclosure configurations and shapes can be used in otherembodiments. A lockable door 202 can be included to protect the innercomponents and prevent access to the power components, and can beopenable using a handle 203. FIG. 6 illustrates a dead front 204 whichis located behind the door 202 and is exposed when the door is opened,to protect operators from the current and voltage of the system.

A number of circuit breaker handles 206 are exposed for access by anoperator in this embodiment, which can be exposed by an opening 208 inthe dead front 204. Each handle 206 is connected to a circuit breakerconnected between a corresponding input power line and output power linein the system 200. Each handle 206 can be flipped or otherwise activatedby an operator to open an associated circuit breaker switch connected toan associated power line, thereby disconnecting the associated outputpower line from the power source providing power on the associated inputpower line. Some embodiments can include an additional safety mechanismto prevent opening the dead front 204 unless all the input power linesare disconnected from their associated output power lines. For example,a master rotary switch (not shown) can be used to disconnect all powerto all lines.

FIGS. 7A and 7B are side and front views, respectively, of the interiorof the safety disconnect system 200 including circuit breakers. Thefront view of system 200 shown in FIG. 7B has the dead front 204removed. System 200 includes multiple circuit breakers 220 arranged inapproximately linear vertical column layout with respect to the sideview of FIG. 7A. The circuit breakers 220 are also arranged such thatthey are positioned in an approximate vertical column with respect tothe front view of FIG. 7B. Other positional arrangements of circuitbreakers 220 can be provided in other embodiments.

Each circuit breaker 220 has a terminal 224 connected to an associatedinput power line 226 on one side of the circuit breaker, and has aterminal 228 on the other side of the circuit breaker connected to anassociated output power line 230. In some embodiments, the power lines226 and 230 can be routed into the enclosure 201 via an opening in abottom panel 232 of the enclosure 201, such that these power lines arenot exposed and do not need to be enclosed in a protective cladding orother protection or safety barrier.

Each circuit breaker 220 includes a handle 206 that is accessiblethrough the dead front 204 as described above. For some embodiments, thehandle 206 can be flipped between two positions to open and close theassociated switch. Other embodiments can provide other types of switchmechanisms instead of handles, such as buttons, levers, dials, etc. Anoperator can flip or otherwise activate a handle 206 on a circuitbreaker 220 to disconnect/reconnect the associated input power linefrom/to the associated output power line, thereby disconnecting orconnecting the associated output power line 230 from or to thecorresponding input power line 226. Each circuit breaker 220 also hasthe ability to automatically trip and disconnect the input power linefrom the associated output power line if a fault condition is detected,such as an amount of current sensed on an input power line that is overa predetermined threshold amount, and can be reset by an operator toreconnect the input and output power lines for the tripped circuitbreaker.

In some embodiments, a central disconnect switch can be added as asafety feature to the enclosure 200. For example, all of the input powerlines and output power lines can be connected to the central switch,such that all power lines can be disconnected using the single centralswitch. This central switch can be provided on the dead front 204 or onthe outside door 203, and can prevent the opening of the dead front ordoor unless the central switch is opened to disconnect all the input andoutput power lines in the enclosure. For example, the central switch caninclude a rotatable handle similar to the enclosure 100 of FIG. 3, orother type of switching mechanism.

Similarly to the embodiment of FIGS. 4A and 4B, system 200 can includecurrent monitoring. For example, a current monitoring sensor 240 can beconnected to each circuit breaker 220 or power line to monitor thecurrent flowing into, through, or out of the circuit breaker or powerline. For example, in some embodiments, a Hall Effect sensor can bepositioned around the jumper connection between two of the poles of thecircuit breaker, as shown, or other types of sensors can be used.Alternatively, the sensors 240 can be connected to the input wires 226or the output wires 230 or at the input or output terminals of thecircuit breaker. The sensors can provide sensor signals to one or morecontrollers via a wired or wireless connected to provide output to anoperator indicating the current magnitudes flowing through the circuitbreakers 220 and/or power lines as sensed by the sensors.

FIG. 8 is a detail view of an alternate embodiment of a connectionadaptor 300 which can be used with some embodiments of a safetydisconnect system. Connection adaptor 300 includes an extension portion302 which is connected to terminal 304 of a disconnect switch 306. Forexample, the terminal 304 can be a terminal 124 or 128 of a disconnectswitch 120 of the embodiment of FIGS. 4A-4B, or a terminal 224 or 228 ofa circuit breaker 220 of the embodiment of FIGS. 7A-7B. The connectionadaptor 300 can be connected to the input terminal or the outputterminal of the switch 306, or both terminals in other embodiments.

The connection adaptor 300 also includes a terminal 308 for receiving aninput or output power line 310, such as a power line 126 or 130 shown inthe example of FIGS. 4A-4B or a power line 226 or 230 in the example ofFIGS. 7A-7B. A conductive end portion 312 of the power line 310 can beinserted into the terminal 308 and tightened by screws (not shown) orotherwise physically secured within the terminal 308. The adaptorincludes conductive material such as copper, aluminum, or otherconductive metal or other material, and creates an electrical connectionbetween the terminal 308 and the cable 310.

The power line 310 has a lengthwise axis A extending down its length atthe conductive end portion 312, and the terminal 304 and extensionportion 302 have a lengthwise axis B extending in the direction of theirorientation, i.e., the direction for terminal 304 that receives aconductive end of a wire. The lengthwise axes A and B are oriented atdifferent angles as shown in FIG. 8. The terminal 308 is oriented toreceive the end portion 312 of the power line 300 at an angle θ withrespect to the extension portion 302, i.e., an angle θ between thelengthwise axes A and B. In the example shown, this angle θ is about 90degrees, but can be other angle values in other embodiments.

The angle θ allows a cable 310 to be attached to a terminal input oroutput (such as on a switch 306 or other terminal device or structure)without having to bend the cable 310 to fit it into the standardterminals which are oriented horizontally in the configuration shown inFIG. 8 (i.e., an angle θ of about zero degrees). Bending of the cable310 as required for many prior power switch systems adds a significantamount of assembly time to a disconnect system, since typical powercables are thick and not easily bent, especially when cables having asolid core conductor are used. Furthermore, the cables may have to befit into tight spaces on either side of the switches 306 or terminals304. The adaptor 300 allows easier installation of cables, especially inmultiple-switch systems.

The connection adaptor 300 has additional advantages. For example, theadaptor 300 can be made of a material that creates a thermal barrierthat can reduce stress on the switch 306 and allow the connected cableto reach higher temperatures. For example, a common temperature ratingfor switches 306 is 75 degrees Celsius, which requires that theconnected cables not reach more than 75 degrees. When using the adaptor300, the connected cable 310 can reach greater temperatures, such as 90degrees Celsius, without damaging the switch 306 since the thermalbarrier of adaptor 300 protects the connected switch 306. This allowssmaller, less expensive cables to be used, since smaller cables reach ahigher temperature for the same amount of current.

In some embodiments, fins or other thermal or heat-dissipationstructures can be attached to or included on the adaptor 300 similarlyto heatsinks to allow even greater heat dissipation (e.g., via air),thus increasing the thermal barrier further.

The described safety disconnect system is a compact, low-cost disconnectsolution for a power system that allows multiple switches for powerlines to be integrated into a single easily-installed enclosure. Somedisconnect system embodiments can also conveniently include currentsensing and monitoring. The inclusion of multiple power lines in asingle enclosure allows a current monitoring system to be provided muchmore cheaply and easily than if multiple disconnect enclosures are used,e.g., a single controller can be connected to multiple sensors withinthe enclosure. The advantageous size, cost, functions, and safetyfeatures of the described safety disconnect system reduces labor andexpense compared to the enclosures used previously.

Although the present invention has been described in accordance with theembodiments shown, one of ordinary skill in the art will readilyrecognize that there could be variations to the embodiments and thosevariations would be within the spirit and scope of the presentinvention. Accordingly, many modifications may be made by one ofordinary skill in the art.

What is claimed is:
 1. A safety disconnect system for a power system,the safety disconnect system comprising: an enclosure operative toreceive a plurality of input power lines into the enclosure and providea plurality of output power lines out of the enclosure, each input powerline coupled to and paired with a corresponding one of the output powerlines, wherein each input power line and output power line is operativeto provide power from a power source; and a plurality of multi-poleswitches provided in the enclosure, wherein the multi-pole switches eachinclude a rotatable handle, each multi-pole switch of the plurality ofmulti-pole switches coupled between an associated one of the pairs ofinput power line and output power line, each multi-pole switch operativeto disconnect the associated input power line from the correspondingoutput power line, wherein the multi-pole switches are accessible behindan opening door of the enclosure, wherein a safety panel is positionedbehind the door and surrounding the multi-pole switches, the safetypanel blocking access to connections of the input power lines and outputpower lines within the enclosure, wherein the safety panel is openableby an operator only in response to opening all of the multi-poleswitches such that all of the input power lines and output power linesare disconnected.
 2. The safety disconnect system of claim 1, whereineach multi-pole switch is operative to disconnect the associated inputpower line from its corresponding output power line independently of theconnections of the other input power lines and output power lines. 3.The safety disconnect system of claim 1, wherein the enclosure islocated on a ground surface, and wherein the enclosure includes a bottompanel operative to allow the input power lines and the output powerlines to be routed into the enclosure from the ground surface throughthe bottom panel.
 4. The safety disconnect system of claim 1, whereineach of the multi-pole switches is included in a circuit breaker.
 5. Thesafety disconnect system of claim 1, further comprising a currentsensing system operative to sense a current flowing through each pair ofinput power line and output power line.
 6. The safety disconnect systemof claim 1, wherein at least one of the input power lines and outputpower lines includes an adaptor coupled between the at least one powerline and the associated multi-pole switch, the adaptor including a bendto allow connection between an end of the at least one power line and aninput terminal having lengthwise axes at different angles.
 7. The safetydisconnect system of claim 6, wherein the adaptor is operative toprovide a thermal barrier protecting the associated multi-pole switchfrom heat generated on the at least one power line connected to theadaptor.
 8. The safety disconnect system of claim 1, wherein the inputpower lines receive power from at least one solar panel.
 9. The safetydisconnect system of claim 8, wherein the input power lines areconnected to at least one string combiner that receives power from atleast one solar panel.
 10. The safety disconnect system of claim 8,wherein the output power lines are connected to at least one recombinerthat combines the output power lines into a lesser number of powerlines.
 11. A method for providing a safety disconnect system, the methodcomprising: providing an enclosure operative to receive a plurality ofinput power lines into the enclosure and provide a plurality of outputpower lines, each input power line coupled to and paired with acorresponding one of the output power lines, wherein each input powerline and output power line is operative to provide power from a powersource; and providing a plurality of multi-pole switches in theenclosure, each multi-pole switch of the plurality of multi-poleswitches connecting an associated one of the input power lines to acorresponding one of the output power lines and operative to disconnectthe associated input power line from the corresponding output powerline, wherein the multi-pole switches are accessible behind an openingdoor of the enclosure, and wherein a safety panel is positioned behindthe door, the safety panel blocking access to connections of the inputpower lines and output power lines within the enclosure, wherein thesafety panel is openable by an operator only in response to opening allof the multi-pole switches such that all of the input power lines andoutput power lines are disconnected.
 12. The method of claim 11, whereinthe enclosure is located on a ground surface, and wherein the inputpower lines and the output power lines are routed into the enclosurefrom the ground surface through a bottom panel of the enclosure.
 13. Themethod of claim 11, wherein each of the multi-pole switches is coupledto one of the following: a rotatable multi-pole switch and a circuitbreaker.
 14. The method of claim 11, further comprising sensing acurrent flowing through each pair of input power line and output powerline.
 15. The method of claim 11, wherein at least one of the inputpower lines and output power lines includes an adaptor coupled betweenthe at least one power line and the associated multi-pole switch, theadaptor including a bend to allow connection between an end of the atleast one power line and an input terminal having lengthwise axes atdifferent angles.
 16. The method of claim 11, wherein the input powerlines receive power from at least one solar panel.